1. Field of the Invention
The present invention is intended to be used at telecommunication systems, for instance radio based access networks in which powerful and simply constructed network components, preferably repeaters, are included.
2. Discussion of the Background
The present invention shows how signalling can be superimposed on existent DECT Digital European Cordless Telecommunications-signalling. The invention can also be used on other systems with similar access method as DECT.
DECT uses TDMA/TDDD/MC, i.e. Time Division Multiple Access/Time Division Duplex/MultiCarrier, which is schematically shown in FIG. 1, which illustrates the division and use in time and frequency in DECT. Along the x-axis is shown a frame consisting of 12+12 time slots for down and uplink respectively, and along the y-axis is shown the 10 carrier channels, i.e. the division in frequency. In DECT these slots may be utilized very freely; because DECT is intended to be selfplanning etc there are no real obstructions for using all the slots in a frame for, for instance a down link.
TDD in classification in up and down link on the "same" carrier and MC in the using of more than one carrier. The TDMA-structure can be said to be in the division in time slots for up and down link.
The technical problem consists of the fact that there for some services are needs for sending short messages within a DECT-system without needing to allocate a special time slot for this and without the need to allocate more frequency space.
With a DECT-system is in this connection referred to Fixed Parts (FP; an FP can consist of a CFP, Central Fixed Part and one or more remote fixed part RFP. RFP and or FP can be described as "base stations" in DECT), Repeaters (sometimes called FR; Fixed Repeaters) and Portable Parts (PP). With short messages is referred to a short string of characters intended for for instance identification (of base stations repeaters or other radio based network elements) etc, or special messages of for instance broadcast type. Some of the equipment which can receive or transmit these messages shall be simple, and is not intended to contain any digital signal processing of the contents in separate time slots (typical examples of this are repeaters).